Martha has $20 to spend on a t-shirt. She has a coupon for 20% off. The t-shirt regularly sells for $22.50 plus 10% sales tax.

Choose all that correctly compute the cost of the t-shirt.

Martha takes 20% of $22.50 and subtracts that amount from the regular price. She takes 10% of the discounted selling price and adds it back to find the purchase amount.
Martha takes the difference between the 20% discount and the 10% sales tax and subtracts 0.10 from 1, and then multiplies that by the regular price.
Martha takes 80% of the regular purchase price of $22.50, and then computes 110% of the reduced price.